Our long-term goal is to understand the genetic and molecular elements that determine the process of aging and life span. The focus of this proposal is to identify molecular genetic effectors that mediate calorie/dietary restriction (CR/DR) life span extension as a prerequisite to developing molecular genetic and pharmacological interventions that can extend healthy life span. Examination of CR/DR in a variety of species shows changes in a large number of genes and physiological systems. A central question in translating this information to therapeutic interventions is which of the many changes seen are involved in extending healthy life span? In flies molecular genetic studies have led to a model in which a portion of the life span extending effect of CR/DR is mediated by alterations in the activity of the histone deacetylases Rpd3 and Sir2, and the transcription factor p53. This model provides a framework for use in identifying genetic, biochemical, and pharmacological effectors of CR/DR mediated longevity. In this proposal we will (i) further examine the mechanisms by which an increase in dSir2 extends life span in the fly, (ii) confirm the life span extending effect of a gene identified through our genomic analysis of the CR/Sir2/p53 pathway and begin to determine it's relationship to CR/DR life span extension, (iii) utilize genome based tools to determine genes and gene sets important for CR/DR life span extension in flies and (iv) test the effect of these newly identified genes on life span using molecular genetic tools.